btrfs-progs: Record highest inode number before repair.

Record highest inode number before inode repair.

This is especially important for corrupted leaf case.
Under that case, if use btrfs_find_free_objectid, it may find a ino
existing in corrupted leaf but dropped by btree_recover.
If that happens, created dir will be referenced incorrectly since there
may be inode_ref or dir_index/item refers to it.

So we must record the highest inode number according to the inode_cache.
Inode_cache is OK since when a inode_ref or dir_index/item is found even
the referenced source is not found, it will be created.
If we record the highest inode number of inode_cache, and use
highest_inode + 1 as 'lost+found' dir, it will ensure the newly created
dir not conflicting with any possible inode.

This provides the basis for nlink or inode rebuild for repairing btrfs
with leaf/node corruption.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

1 files changed, 15 insertions, 0 deletions

diff --git a/cmds-check.c b/cmds-check.c
index d57363c1..3d3d8d79 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -1927,6 +1927,21 @@ static int check_inode_recs(struct btrfs_root *root,
 	}
 
 	/*
+	 * We need to record the highest inode number for later 'lost+found'
+	 * dir creation.
+	 * We must select a ino not used/refered by any existing inode, or
+	 * 'lost+found' ino may be a missing ino in a corrupted leaf,
+	 * this may cause 'lost+found' dir has wrong nlinks.
+	 */
+	cache = last_cache_extent(inode_cache);
+	if (cache) {
+		node = container_of(cache, struct ptr_node, cache);
+		rec = node->data;
+		if (rec->ino > root->highest_inode)
+			root->highest_inode = rec->ino;
+	}
+
+	/*
 	 * We need to repair backrefs first because we could change some of the
 	 * errors in the inode recs.
 	 *